A new DNA recombinant vaccine was administered in two dosages (5 and 10 mcg) to 60 health care workers to assess safety and immunogenicity. In addition, it was given at a higher dosage (100 mcg) to 60 dialysis patients and was used to treat 25 health care workers who did not respond to the licensed plasma-derived vaccine. A booster dose of 10 mcg for health care workers and 100 mcg for dialysis patients is currently being administered to anyone who failed to develop or maintain an anti-HBs level of >10 mIU. New formulations of the recombinant vaccine will also be tested in dialysis patients.